I’ll give it a quick go:
>>”WHY is sola Scriptura not valid? “
Scripture *alone* doesn’t exist in reality. E.g., in your case, you’re reading it and getting some meaning from it, different meaning than someone else might. So it’s never really scripture alone.
Secondly, it fails it’s own test. If you mean by sola scriptura that “scripture alone is entirely sufficient for all doctrine...” that doctrine is not in scripture. So the doctrine is self-contradicting.
Thirdly in fails in practice to result in the most basic requirement of “One Lord, one faith, one baptism.”
In summary, sola scriptura is a concept, not a reality; it is unscriptural and internally contradictory and it fails in practice.
Of course it is. If one sincerely is seeking Gods truth asking the Holy Spirit to guide them He will get from scripture exactly what God wants that person to get. The problem with Catholics and those who follow a church is that they are not listening to the Holy Spirit but are listening to men.
Of course those that insist that the notion that Sola Scriptura is false cling to the absurd concept of Sola Ecclesia, which is not even hinted at in Scripture. Why? Because they say so.